脱式计算 54÷[6.3-13/4×(12/3+19/21)]; 8.8÷21/5×(1.05÷31/2).

问题描述:

脱式计算
54÷[6.3-1

3
4
×(1
2
3
+
19
21
)];
8.8÷2
1
5
×(1.05÷3
1
2
).

①54÷[6.3-1

3
4
×(1
2
3
+
19
21
)]
=54÷[6.3-
7
4
×
18
7
]
=54÷[6.3-4.5]
=54÷1.8
=30;
②8.8÷2
1
5
×(1.05÷3
1
2

=8.8÷2
1
5
×0.3
=4×0.3
=1.2.